1. Field of the Invention
The present invention relates to a balloon assembly, and has particular, but not exclusive, reference to a balloon assembly of the type applicable as part of a speaker system.
2. Statement of the Prior Art
As well-known in the art, a speaker comprises a vibrating element such as a horn or vibrating plate and a horn. The vibrating element is used to convert a change in the electrical vibrations given to mechanical vibrations, while the horn is adapted to amplify the latter vibrations, thereby to increase efficiency and acoustic output.
For the vibrating element, a variety of elements such as those of moving coil type, moving iron type, crystal type and condenser type have been used for the purposes intended. The vibrating element used has been decreased in size and, in recent years, has been constructed from a small thin plate having a diameter of 20 .phi. or lower, in particular. The old vibrating element is of a three-dimensional form comprising a vibrator such as a vibrating plate or corn and an oscillator such as an electromagnet or permanent magnet. However, the conventional thin vibrating element has a vibrator which is designed to serve as an oscillator as well, and is of a plane form that apparently comprises a single thin plate. This thin vibrating element may therefore find wider use than the old one does, since it does not virtually require any special space for its attachment. In actual applications, however, this thin vibrating element has only find its use for systems such as telephone speaker systems, where the vibration sound is caught close to an ear with no horn attached. This is because of the absence of any suitable means for sufficiently amplifying the vibrations.
To the old vibrating element comprised of a vibrator and an oscillator, as mentioned above, a horn can be attached, since the vibrator works smoothly even when that element is mounted on a supporting member. When a horn is attached to the thin plate type vibrating element, however, the vibrating element behaves as if it is attached as such to the horn, partly because the vibrator per se thereof serves as the oscillator. Thus, the horn functions only as a supporting member, thus failing to produce an amplifying function. For that reason, there has been demand for the development of methods for amplifying the vibrations of this plate type vibrating element and thereby obtain sufficient acoustic output.
Another disadvantage of the thin plate type vibrating element is that there is no suitable method for attaching it to a balloon in the case that the balloon is applied as part of a speaker system, as disclosed in Japanese Patent Application No. 61-275885 specification.